Plate-tube type heat exchanger

ABSTRACT

A plate-tube type heat exchanger not requiring maintenance is described, comprising: a plate with a plurality of channels running parallel along thereof; and, a plurality of tubes housed and secured to said channels, thus forming a circuit for the circulation of a heating fluid, a cooling fluid or a means of heating; the plate includes integrally attachment means associated to each channel, which in their closed position, cover along with its corresponding channel, almost the entire tube external perimeter housing in said channel, thereby securing each of the tubes to the whole plate, without the use of welding and a large contact surface is achieved for the heat conduction between the plate and each one of the tubes.

The present application is a division of co-pending parent applicationSer. No. 10/482,032, filed Jun. 7, 2004, itself a national phase of aPCT application PCT/MX02/00057, filed Jun. 26, 2002.

FIELD OF THE INVENTION

The present invention relates to techniques employed in designing andmanufacturing heat exchange equipment, and more particularly, it isrelated to a plate-tube type heat exchanger not requiring maintenance.

BACKGROUND OF THE INVENTION

Generally, plate-tube type heat exchangers are comprised by a pluralityof tubes and plates, which are bonded to each other by mechanicalfastening or tack welded in order to shape the exchanger structure.

Particularly, such heat exchangers are used as condenser and evaporatorin domestic and commercial refrigeration systems, they can also be foundon water heaters by means of solar energy, air heaters including insidethe tubes, an electric resistance, natural convection static condensers,forced air condensers, natural convection static evaporators and forcedair evaporators.

In spite of the widely spread use of these equipments, they have beenobserved as presenting some drawbacks. In first instance, it may be saidthat manufacturing process of these equipments is quite complex, sinceupon being comprised of multiple components, steps to assemble them areburdensome, such as the bonding step between tubes and plates via tackwelding, in which it is necessary to bond the tubes one by one to theplates.

Likewise, such a traditional method of binding tubes and plates is notthat suitable for the equipments previously mentioned to achieve aefficient heat transfer between the environment and the heating orrefrigeration fluid which is inside the tubes, particularly, because thecontact surface between tubes and plates is significantly reduced, asmay be seen in FIG. 1, showing a cross sectional cut of a “halfcoverage” type assembly used in plate-tube type heat exchangers of theprior art. In such an assembly, a tube is housed in a plate channel,remaining fixed and contacting directly therewith only through a weldingpoint.

A variant of this traditional method of assembly by welding can beappreciated in FIG. 2, (total coverage), wherein a pair of platessimilar to those in FIG. 1 are welded to each other by welding tacks,enclosing the tube between the channel thereof. This variant is neitherefficient, since most of times the tube does not fit correctly the spaceformed by the plate channels, thus having a little direct contactbetween plates and tube for heat conduction.

On the other hand, there is an additional problem related to maintenanceand cleaning of these equipments, specially forced air condensers whichinclude fins, such as those used in domestic or commercial refrigerationsystems. In said condensers, spacing between fins is significantlyreduced, generally between 2 to 3 mm, which favors adhesion andaccumulation of dust, grime and crap therebetween. Said accumulationbecomes so important that in many cases, the air passage through finsmay be obstructed, thereby causing reduction in condenser's heatexchange ability with the environment and consequently, therefrigeration system stops functioning and cooling properly, affectingother elements of the refrigeration system. Additionally, cleaning saiddust or grime adhered to the fins is made difficult due to the spacequite reduced existing between fins.

Thus, in the state of the art, it may be found systems which intent toreduce on one hand, the assembly steps of these heat exchangers, such isthe case of evaporator described in U.S. Pat. No. 2,212,912, which isformed from an extruded sheet integrally including tubes and fins.However, in order to give the evaporator a final shape, the tubesincluded in said plates need to be welded to a header or headers usingseveral accessories. Similarly, when it is desired to form condenserswith a higher capacity, it is necessary to weld bonding two extrudedsheets or to change the size of extrusion die used to manufacture saidsheets, thus increasing manufacturing costs.

On the other hand, the European Patent No. 0157370, is directed to apanel for an evaporator or condenser heat exchange, said panel is alsoformed from an extruded sheet which includes a plurality of oval-shapegrooves in cross section; inserting a tube in each of said grooves, saidtube undergoes a plastic deformation at its circular wall to refill andto fit the oval contour of the groove walls, thus remaining fixedinside, reason why it is not necessary to use welding in order to bindtubes to the extruded sheet. However, when it is desired to bind twopanels to form a larger condenser, this document only provides the useof a piping to connect both panels, without mentioning the existence ofa direct and firm bonding therebetween; this lack does not allow tomanipulate such panels together so as to form different condenser orevaporator configurations and arrangements.

Finally, both documents from the prior art, do not consider among itsobjects to form a heat exchanger, on which said problems regardingadhesion, accumulation, and dust and grime cleaning between itscomponents are minimized, which as mentioned above, decrease thecapacity of equipment performance.

An additional prior art document is U.S. Pat. No. 2,732,615, related toa method for securing a tube to a metal plate, whereby the plate isdeformed to form a channel, and further to the placement of a tube insaid channel, pressing the plate against the tube in order to deform itand secure it. This document does not show how to join two or moreplates in order to form a tridimensional heat exchanger, neither itindicates the employment of alternative extruded plates.

Accordingly, it has been sought to suppress the drawbacks of thetube-plate-type heat exchangers from the current art, and to provide atube-plate-type heat exchanger not requiring maintenance, of a verysimple and convenient construction, which allows to reduce the number ofcomponents and work used during its manufactures, thus eliminating theuse of welding to join the tubes and plates, or to join two or moreplates to each other, in which cleaning of dust and grime that may beadhered and accumulated between its components is easy.

OBJECTS OF THE INVENTION

Having in mind the prior art drawbacks, it is an object of the presentinvention to provide a tube-plate-type heat exchanger not requiringmaintenance, involving a single assembly process during itsmanufacturing.

An additional object of the present invention, is to provide atube-plate-type heat exchanger not requiring maintenance, wherein thereis a large contact surface between tubes and plates.

A further object of the present invention, is to provide atube-plate-type heat exchanger not requiring maintenance, whereinwelding to firmly join tubes to plates is not used.

Yet another object of the present invention, is to provide atube-plate-type heat exchanger not requiring maintenance, wherein two ormore plates can be firmly joined to each other, without the use ofwelding.

It is even a further object of the present invention, to provide atube-plate-type heat exchanger not requiring maintenance, whereincleaning of dust and grime that may be adhered between its components iseasy.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features of the present invention are set forth withparticularity in the appended claims. The invention itself, however,both for its organization and for its operating method, together withfurther objects and advantages of the invention, will be best understoodby reference to the following description of specific embodiments, whentaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a cross sectional view of a “half coverage” assembly, used inthe tube-plate-type heat exchangers of the prior art.

FIG. 2 is a cross sectional view of a “total coverage” assembly, used inthe tube-plate-type heat exchangers of the prior art.

FIG. 3 is a top perspective view of a tube-plate-type heat exchanger notrequiring maintenance, constructed in accordance with the principles ofthe present invention.

FIG. 4 is a partial cross sectional view of the plate of thetube-plate-type heat exchanger in FIG. 3, which includes a tube housedand secured in one of the channels thereof.

FIG. 5 is a top perspective view of the plate with the tube housed andsecured, shown in FIG. 4.

FIG. 6 is a top perspective view of a second configuration that mayadopt the tube-plate-type heat exchanger of the present invention.

FIG. 7 is a top perspective view of a tube-plate-type heat exchanger notrequiring maintenance, constructed in accordance with a firstalternative embodiment of the present invention.

FIG. 8 is a cross sectional view of an extruded profile plate of theheat exchanger shown in FIG. 7.

FIG. 9 is a cross sectional view of the extruded profile plate shown inFIG. 8, including tubes housed and secured in the plate channels.

FIG. 10 is a top perspective view of the extruded profile plate in FIG.9.

FIGS. 11 and 11A, are cross sectional views for showing the assemblybetween two extruded profile plates with tubes housed and secured.

FIG. 12 is a perspective view of a second configuration that may adoptthe embodiment shown in FIG. 7.

FIG. 13 is a perspective view of a tube-plate-type heat exchanger notrequiring maintenance, constructed in accordance with a secondalternative embodiment of the present invention.

FIG. 14 is a cross sectional view of one of the extruded profile plateof the heat exchanger shown in FIG. 13.

FIG. 15 shows a top perspective view of the plate illustrated in FIG.14.

FIGS. 16 and 16A, are cross sectional views for showing the assemblybetween two extruded profile plates, as shown in FIG. 14.

FIGS. 17 and 17A, are exploded views showing the connection of pipingand/or accessories to the extruded profile plate shown in FIG. 15.

FIG. 18 shows a top perspective view of a second configuration that mayadopt the alternative embodiment shown in FIG. 13.

DETAILED DESCRIPTION OF THE INVENTION

Referring in detail to the accompanying drawings, in FIG. 1 is shown a“half coverage”-type assembly 10 used in plate-tube type heat exchangersof the prior art. In said assembly, a tube 11 is housed in the channel14 of a plate 12, remaining fixed and making a direct contact to it onlythrough a welding point 13.

In this sense, in FIG. 2 a “total coverage” type assembly used in theprior art is shown. In such assembly, a pair of plates 12′ are weldedeach other via welding points 13′, enclosing tube 11′ between channels14′ thereof. However, in many cases, the tube 11′ does not fit suitablythe space formed by plate channels 14′, thus having a little directcontact between plates and tube for heat conduction.

On the other hand, specific reference is now made to FIG. 3, in which aplate-tube type heat exchanger 100 not requiring maintenance is shown,as constructed according to a particularly specific embodiment of thepresent invention, which must be considered as illustrative rather thanlimitative.

In general terms, the plate-tube type heat exchanger 100 comprises: aplate 110 with a plurality of channels 111 running parallel alongthereof; and, a plurality of tubes 120 housed and secured to saidchannels 111, thus forming a circuit for the circulation of a heatingfluid, a cooling fluid or a means of heating. Plate 110 includesintegrally attachment means 112 associated to each channel, as shown inFIG. 4; which in their closed position, cover along with itscorresponding channel, almost the entire tube external perimeter housingin said channel, thereby securing each of the tubes 120 to the wholeplate, without the use of welding and at the same time, a large contactsurface 113 is achieved for the heat conduction between plate 110 andeach one of the tubes 120, as can be seen in FIGS. 4 and 5.

On this respect, the plurality of attachment means 112, are preferablylongitudinal plates from the same plate formed by mechanical means, andextending from both sides of each one of the channels 111. In thisembodiment, channels 111 are preferably semicircular or “C”-shaped inits cross section; such that when said attachment means 112 are in theirclosed position, they function as a mechanical clamp which inconjunction with its corresponding channel cover at least 270°approximately of the tube external perimeter 120 housed in said channel,thereby impeding in the entire plate the free movement of each one ofthe tubes 120 and a large contact surface 113 is generated for heatconduction between the plate and each one of the tubes 120, providedthat such components make full contact without using welding.

This particular form of attachment between tubes and the plateeliminating the use of welding, allows the construction of heatexchangers of different configurations, such as the “coil” shapestructure shown in FIG. 3 or the “snail” shape structure of FIG. 6.

Particularly, plate 110 With the tubes secured is observed in FIG. 3,including a folding 140 at a determined distance, through its crosssection at an angle of about 180°, forming a “coil” shape structure,wherein the minimum spacing distance between segments of the platelocated at each side of said folding is at least of 20 mm. Morespecifically, it is preferred that said spacing distance be between 20mm to 30 mm, thereby obtaining a compact exchanger, with a large area ofheat exchange, allowing a free passage of air therethrough, andpreventing mostly the adhesion and accumulation of dust, rubbish, orgrime on its surface. Therefore, the exchanger is suitable to be used asa forced air condenser in commercial and/or domestic refrigerationequipments, such as food and beverage refrigerators and freezers.

In FIG. 6, a heat exchanger 100′ is shown with an arrangement in “snail”shape, in which the plate 110′ with secured tubes, includes everydetermined distance, a folding 140′ through its cross section at anangle of approximately 90°, thus forming a “coil” or “snail” shapestructure, whose walls are spaced each other a minimum distance of atleast 20 mm, preferably such a spacing distance is from 20 mm to 30 mm,achieving a compact structure, of a large area of heat exchange, inwhich dust, grime and rubbish that might be adhered, does not obstructair circulation between exchanger walls, being suitable to be used as aforced air condenser in commercial and/or domestic refrigerationsystems.

Finally, it is important to establish that in heat exchangers 100 and100′, tube ends 121 and 121′ protrude from the plate to make thenecessary input and output connections with the rest of the system.Regarding the manufacturing materials of these exchangers components,both the plate 110 and 110′ and tubes 120 and 120′ are made of iron,galvanized iron, aluminum, copper or the like.

Referring now particularly FIG. 7, a heat exchanger 200 of theplate-tube type not requiring maintenance is shown, constructed inaccordance to a first particularly preferred embodiment of the presentinvention, which comprises in general: a plurality of extruded profileplates 210 joined to each other, each one including a plurality ofchannels 211 running parallel along the plate; and, a plurality of tubes220 housed and secured in said channels 211, thus forming a circuit forthe circulation of a heating fluid, a refrigeration fluid or a means ofheating. The extruded profile plates 210 include integrally attachmentmeans 212 associated to each channel, such as shown in FIG. 8, which intheir closed position, cover together with its corresponding channelalmost fully the external surface of tube housed in said channel;thereby securing each one of the tubes 120 to each one of said plates210, without the use of welding and at the same time, a large contactsurface 213 is generated for the heat conduction between plates 210 andeach one of the tubes 220. Likewise, said extruded profile plates 210include integrally in their ends parallel to the channels, couplingmeans 214, to be firmly joined to each other, without using welding. Allof the above mentioned, may be observed in FIGS. 8 and 9.

Additionally, it may be said that in the open position of suchattachment means 212, these are extended from both sides of itscorresponding channel, forming therewith a “U” shape housing in crosssection, and where such attachment means 212 are in its closed position,they work as a mechanical clamp which along with said channel, cover atleast 270° of the external perimeter of tube 220 housed in the channel,thereby impeding in each one of the plates free movement of tubes and alarge contact surface 213 is generated for heat conduction between tubesand plates, provided that such components make full contact withoutusing welding, as may be seen in FIGS. 9 and 10.

Referring to the plate, its surface may be flat or wavy, being preferredto use a wavy surface plate, which allows increasing the effective areaof heat transfer, compared to a flat plate.

With respect to the coupling means 214, it may be mentioned that theyare located at the plate ends parallel to channels 111, and arepreferably of the “male-female” type. Specifically, when it is desiredto join two extruded profile plates 210 to each other, the male end ofone of them is introduced into the female end of the other, which closesthereafter by means of pressure, thus achieving to firmly join two ormore extruded profile plates 210 without using welding, which alsoallows a contact surface to exist for the heat conduction betweenplates, such as may be observed clearly in FIGS. 11 and 11A.

This particular way of attachment between tubes and plates by attachmentmeans 212, as well as the easiness to join two or more extruded profileplates by such coupling means 214, which eliminate the use of welding,allow to build heat exchangers of very different configurations andsizes, such as those shown in FIGS. 7 and 12, both configurationspresenting most of the characteristics mentioned for the exchangers ofFIGS. 3 and 7 previously described. Specially, exchangers 200 and 200′of this first embodiment, maintain such minimal spacing distance betweenwalls formed by the plate, which is alt least 20 mm, more preferablybetween 20 mm to 30 mm. Likewise, its principal application is as forcedair condensers used in domestic and commercial refrigeration equipments.

Concerning the manufacturing materials, it may be mentioned that theplate is made preferably of aluminum, provided that such material iseasy to handle under the extrusion processes known in the prior art. Onthe other hand, the tubes may be manufactured in iron, copper oraluminum.

Additionally, referring particularly to FIG. 13, a plate-tube type heatexchanger 300 not requiring maintenance, constructed in accordance to asecond preferred embodiment of the present invention is shown, generallycomprising: a plurality of extruded profile plates 310 joined to eachother, each one including integrally a plurality of tubes or ducts 311,running parallel along the plate, which are interconnected in their endsby connection fixtures 320, forming a circuit for the circulation of aheating fluid, a refrigeration fluid or a means of heating 314 as tofirmly join two plates to each other, without using welding, as shown inFIG. 14.

In such a figure, as well as in FIG. 15, it may be seen that extrudedprofile plate used in this second embodiment is somewhat similar toplate 210 above described, whose surface may be flat or wavy, beingpreferred to use a wavy surface plate, taking advantage at the heattransfer area compared to a flat plate. In this sense, at the internalface of each one of the tubes 311, a plurality of nervures or fines 315is preferably included as to increase the primary contact surfacebetween the heat exchange means and tubes 311 integrally joined to theplate.

On the other hand, it is shown that coupling means are similar to thosepreviously described for plates 210 of the first embodiment, that is,are of male-female type and are located in the plate ends which areparallel to channels. Said coupling means allow to firmly join two ormore plates to each other, without using welding, such as shown in FIGS.16 and 16 A.

Referring now to FIGS. 17 and 17 A, it may be appreciated that in theplate ends 310, tubes integrally included therein, may be interconnectedto each other by connection fixtures 320 of different configurations,such as straight tubes, or U-shaped tubes, which are introduced in tubes311 integrated to the plate and secured thereto in order to form serialand parallel circuits for the heating or refrigeration fluid or heatingmeans.

Once said tubes 311 have been interconnected, plates may be folded inorder to obtain configurations shown in FIGS. 13 and 18, “coil” shapeconfigurations and “snail ” shape configurations, respectively, whosecharacteristics have been previously widely mentioned, including theirmanufacturing materials.

Finally, it should be noted that time and efforts required tomanufacture the heat exchangers of the present invention, is much lessercompared to those known from the prior art, since they essentiallyinclude only plate and tubes of easy assembly.

Even though in the foregoing description certain embodiments of thepresent invention are illustrated and described, emphasis should be madein that numerous modifications are possible to such embodiments withoutdeparting from the true scope thereof, such as varying the number ofextruded profile plates, number of channels or tubes included therein,or how to fold the plate in order to obtain configurations other thanthose previously mentioned, keeping the minimum spacing distance, thuspreventing fouling problems. The present invention, therefore, shouldnot be restricted except for that required by the prior art and by theappended claims.

1. A plate-tube type heat exchanger comprising: a plurality of extrudedprofile flat or wavy plates, each one including integrally a pluralityof tubes or ducts, running parallel along the plate, which areinterconnected in their ends by connection fixtures, forming a circuitfor the circulation of a heating fluid, a refrigeration fluid or heatingmeans, wherein the extruded profile plates include integrally at theirends parallel to the channels, coupling means to firmly join two platesto each other, without using welding, in order to form a heat exchangernot requiring maintenance.
 2. A plate-tube type heat exchanger accordingto claim 1, wherein at the internal face of each one of the tubesintegrated to the plates, a plurality of nervures or fines is included.3. A plate-tube type heat exchanger according to claim 1, wherein saidconnection fixtures are straight tubes, or U-shaped tubes.
 4. Aplate-tube type heat exchanger according to claim 1, wherein thecoupling means are of the male-female type.
 5. A plate-tube type heatexchanger according to claim 4, wherein when it is desired to join twoextruded profile plates to each other, the male end of one of them isintroduced into the female end of the other, which closes thereafter bymeans of pressure, thus achieving to firmly join two or more extrudedprofile plates without using welding, thus generating a surface for theheat conduction between plates.
 6. A plate-tube type heat exchangeraccording to claim 5, wherein the plates joined to each other include afolding at a determined length, through its cross-section at an angle ofabout 180°, forming a coil shape structure, wherein the minimum spacingdistance between segments of the plates located at each side of saidfolding is at least 20 mm, employing optionally between 20 mm to 30 mm.7. A plate-tube type heat exchanger according to claim 6, wherein thestructure of said heat exchanger allows the same to be used as a forcedair condenser in commercial and/or domestic refrigeration equipments, inwhich dust or grime is not accumulated allowing a free passage of air.8. A plate-tube type heat exchanger according to claim 5, wherein theplates joined to each other, include at every determined length, afolding through its cross-section at an angle of approximately 90°, thusforming a coil or snail shape structure, whose walls are spaced eachother a minimum distance of at least 20 mm, optionally such a spacingdistance is from 20 mm to 30 mm.
 9. A plate-tube type heat exchangeraccording to claim 8, wherein the structure of said heat exchangerallows the same to be used as a forced air condenser in commercialand/or domestic refrigeration equipments, in which dust or grime is notaccumulated allowing a free passage of air.
 10. A plate-tube type heatexchanger according to claim 9, wherein the extruded plate includingtubes is manufactured from aluminum.